scholarly journals OFDMA Backoff Control Scheme for Improving Channel Efficiency in the Dynamic Network Environment of IEEE 802.11ax WLANs

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5111
Author(s):  
Youngboo Kim ◽  
Lam Kwon ◽  
Eun-Chan Park
Keyword(s):  
Random Access ◽  
Dynamic Network ◽  
Access Point ◽  
Local Area ◽  
Channel Access ◽  
Signaling Mechanism ◽  
Ieee 802.11Ax ◽  
Channel Efficiency ◽  
Control Scheme ◽  
New Feature

IEEE 802.11ax uplink orthogonal frequency division multiple access (OFDMA)-based random access (UORA) is a new feature for random channel access in wireless local area networks (WLANs). Similar to the legacy random access scheme in WLANs, UORA performs the OFDMA backoff (OBO) procedure to access the channel and decides on a random OBO counter within the OFDMA contention window (OCW) value. An access point (AP) can determine the OCW range and inform each station (STA) of it. However, how to determine a reasonable OCW range is beyond the scope of the IEEE 802.11ax standard. The OCW range is crucial to the UORA performance, and it primarily depends on the number of contending STAs, but it is challenging for the AP to accurately and quickly estimate or keep track of the number of contending STAs without the aid of a specific signaling mechanism. In addition, the one for this purpose incurs an additional delay and overhead in the channel access procedure. Therefore, the performance of a UORA scheme can be degraded by an improper OCW range, especially when the number of contending STAs changes dynamically. We first observed the effect of OCW values on channel efficiency and derived its optimal value from an analytical model. Next, we proposed a simple yet effective OBO control scheme where each STA determines its own OBO counter in a distributed manner rather than adjusting the OCW value globally. In the proposed scheme, each STA determines an appropriate OBO counter depending on whether the previous transmission was successful or not so that collisions can be mitigated without leaving OFDMA resource units unnecessarily idle. The results of a simulation study confirm that the throughput of the proposed scheme is comparable to the optimal OCW-based scheme and is improved by up to 15 times compared to the standard UORA scheme.

scholarly journals Hierarchical Slotted Wireless Random Channel Access with Power Control

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Abdelillah Karouit ◽  
Luis Orozco Barbosa ◽  
Fernando Ramírez-Mireles ◽  
Abdelkrim Haqiq
Keyword(s):  
Power Control ◽  
Power Level ◽  
Random Access ◽  
Packet Transmission ◽  
System Throughput ◽  
Channel Access ◽  
Access Scheme ◽  
Control Scheme ◽  
Average System

This paper introduces a hierarchical Wireless Random Access scheme based on power control where intelligence is split among the mobile users in order to drive the outcome of the system towards an efficient point. The hierarchical game is obtained by introducing a special user who plays the role of altruistic leader whereas the other users assume the role of followers. We define the power control scheme in such a way that the leader_first chooses the lowest power to transmit its packets amongNavailable levels whereas the followers re-transmit by randomly choosing a power level picked fromN-1higher distinct power levels. Using a 3D Markovian model, we compute the steady state of the system and derive the average system throughput and expected packet transmission delay. Our numerical results show that the proposed scheme considerably improves the global performance of the system avoiding the well known throughput collapse at high loads commonly characterizing most random channel access mechanisms.

scholarly journals An Effective Wide-Bandwidth Channel Access in Next-Generation WLAN-Based V2X Communications

2019 ◽  
Vol 10 (1) ◽  
pp. 222 ◽  
Author(s):  
Hanseul Hong ◽  
Young Yong Kim ◽  
Ronny Yongho Kim ◽  
Woojin Ahn
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Packet Transmission ◽  
Intelligent Transport System ◽  
Area Network ◽  
Channel Access ◽  
Next Generation ◽  
Wide Bandwidth ◽  
Channel Efficiency

As Intelligent Transport System (ITS) applications are diversified and amount of ITS data increases, high throughput and reliability are required in next-generation V2X communications. In order to meet such increased throughput and reliability requirements, IEEE 802.11bd, the next-generation V2X communication standard, has commenced standard development. One of the main features of IEEE 802.11bd is a 20-MHz bandwidth transmission. In this paper, a novel wide-bandwidth channel access scheme in next-generation Wireless Local Area Network (WLAN)-based vehicular communications is proposed. The proposed scheme is designed to provide fairness with other ITS devices and channel efficiency considering adjacent channel interference. By using the proposed scheme, through extensive simulations, it is verified that, while satisfying the fairness requirement with other ITS devices, the channel access delay of wide-bandwidth packet transmission can be optimized.

scholarly journals Group-Based Uplink OFDMA Random Access Algorithm for Next-Generation WLANs

2020 ◽  
Vol 38 (1) ◽  
pp. 155-161
Author(s):  
Annan Yang ◽  
Bo Li ◽  
Mao Yang ◽  
Zhongjiang Yan
Keyword(s):  
Multiple Access ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Random Access ◽  
Local Area ◽  
Network Throughput ◽  
Practical Significance ◽  
Area Network ◽  
Ieee 802.11Ax ◽  
Access Channel

The traditional wireless local area network(WLAN) standard, IEEE 802.11, adopts carrier sense multiple access/collision avoidance(CSMA/CA) mechanism to allow a single user to compete for channel access. The upcoming WLAN standard, IEEE 802.11ax, combines orthogonal frequency division multiple access(OFDMA) technology with random access, and use Uplink OFDMA Random Access(UORA) technology as uplink random access. Therefore, UORA which allow multiple users to access channel at the same time can improve the utilization of network resources. Although UORA technology in IEEE 802.11ax has the advantage of low signaling overhead, when the number of users of network is large, the increase of random access collisions will lead to the decrease of network throughput. Therefore, we propose a group-based UORA method. As a central scheduling node, Access Point(AP) divide Stations(STAs) and resources to groups and sets different GroupID for different groups. STAs can only access resources with the same GroupID randomly. The validity of group-based UORA method is verified by mathematical model analysis and simulation. The network throughput of our group-based UORA is higher than that of the original UORA in IEEE 802.11ax, so it has great practical significance.

scholarly journals A Poisson Process-Based Random Access Channel for 5G and Beyond Networks

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 508
Author(s):  
Alaa Omran Almagrabi ◽  
Rashid Ali ◽  
Daniyal Alghazzawi ◽  
Abdullah AlBarakati ◽  
Tahir Khurshaid
Keyword(s):  
Poisson Process ◽  
Random Access ◽  
Communication Technologies ◽  
Channel Access ◽  
Access Channel ◽  
Machine Type Communications ◽  
Equal Chance ◽  
Random Access Channel ◽  
Access Mechanisms

The 5th generation (5G) wireless networks propose to address a variety of usage scenarios, such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Due to the exponential increase in the user equipment (UE) devices of wireless communication technologies, 5G and beyond networks (B5G) expect to support far higher user density and far lower latency than currently deployed cellular technologies, like long-term evolution-Advanced (LTE-A). However, one of the critical challenges for B5G is finding a clever way for various channel access mechanisms to maintain dense UE deployments. Random access channel (RACH) is a mandatory procedure for the UEs to connect with the evolved node B (eNB). The performance of the RACH directly affects the performance of the entire network. Currently, RACH uses a uniform distribution-based (UD) random access to prevent a possible network collision among multiple UEs attempting to access channel resources. However, in a UD-based channel access, every UE has an equal chance to choose a similar contention preamble close to the expected value, which causes an increase in the collision among the UEs. Therefore, in this paper, we propose a Poisson process-based RACH (2PRACH) alternative to a UD-based RACH. A Poisson process-based distribution, such as exponential distribution, disperses the random preambles between two bounds in a Poisson point method, where random variables occur continuously and independently with a constant parametric rate. In this way, our proposed 2PRACH approach distributes the UEs in a probability distribution of a parametric collection. Simulation results show that the shift of RACH from UD-based channel access to a Poisson process-based distribution enhances the reliability and lowers the network’s latency.

scholarly journals ANALISIS TRANSFER RATE WIRELESS LOCAL AREA NETWORK DENGAN STANDAR IEEE 802.11A DAN IEEE 802.11G PADA KANAL LINE OF SIGHT

2016 ◽  
Vol 3 (1) ◽  
pp. 31-39
Author(s):  
F Ammar ◽  
Hanafi Hanafi
Keyword(s):  
Transfer Rate ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Access Point ◽  
Local Area ◽  
Line Of Sight ◽  
Area Network ◽  
Ieee 802.11A ◽  
5 Ghz

WiFi bekerja pada band 2,4 GHz dan 5 GHz. Standar WiFi yang bekerja pada frekuensi ini antara lain IEEE802.11g dan IEEE802.11a. Pada penelitian ini dilakukan pengukuran terhadap transfer rate download dan upload data dengan standar IEEE802.11g dan IEEE802.11a. Pengukuran dilakukan pada kanal Line of Sight (LOS), menggunakan dua buah laptop yang dihubungkan dengan Access Point (AP) standar IEEE802.11g dan IEEE802.11a.  Hasil penelitian diperoleh, pada standar IEEE802.11g, transfer rate download dan upload data tertinggi 2.662,54.KB/s dan 2.549,60 KB/s, dan terendah 484,50.KB/s dan 477,40 KB/s, sedangkan pada standar IEEE802.11a, transfer rate download dan upload data tertinggi 8.104,68 KB/s dan 5.744,24 KB/s, dan terendah 872,24 KB/s dan 465,38.KB/s. Pada standar IEEE802.11g, transfer rate download dan upload data pada sinyal terendah hingga di bawah 35% dan 30%, dari transfer rate download dan upload data tertinggi. Pada standar IEEE802.11a, transfer rate download dan upload data pada kualitas sinyal terendah hingga di bawah 20% dan 30%, dari transfer rate download dan upload data tertinggi. Kemampuan transfer rate download data Standar IEEE802.11a, 2–3 kali lebih baik pada kondisi kualitas sinyal tertinggi, dan tidak lebih dari 2 kali pada kondisi kualitas sinyal terendah, dibandingkan kemampuan transfer rate download data standar IEEE802.11g. Kemampuan transfer rate upload data Standar IEEE802.11a, 1,4–3 kali lebih baik pada kondisi kualitas sinyal tertinggi, dan 1-3 kali lebih baik pada kondisi kualitas sinyal terendah, dibandingkan kemampuan transfer rate upload data standar IEEE802.11g.

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